Syllabus
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Presentations
Homework
a) Decipher the following message. I have used an affine monoalphabetic cipher. Look at frequencies of characters, digraphs and trigraphs before you make a guess.
werddgqmdurofevmtsdjsodxgrdfehmdfmducmwmbgsrxewgzygsddfedieroigzifiengzumoureobmweobgszcur sdmongqqurqerfgszngrqzsrgrdfmdzmexcunnceatmqzmedmlmziuomtsdudiertmcurxrscturqnaxsnnerxwfun mdfmzmezmngdogbgdfmzsruksmwgzygsdoerxksuzyaineoomodgtmfexeddfmqacrgwexeaodfmazmrgdbgzmhmza grmvnsodfmaennzmksuzmednmeodbgzdabuhmcursdmogzerfgszgbagszducmqacoerxodsxugofehmexgvdmxdfm detededmifruksmerxcexmuddfmuzgwrtaexxurqcsouimksuvcmrderxhezugsomlmziuomodgdfmuzineoomotsd dfmducmxurdmzhenodavuiennazmceurdfmoecmubbgnngwmxigzzmidnadfmmlmziuomofgsnxbeduqsmmhmrdfmc godbudqactsrrumo
b) Choose an English text with 500 characters. Write down the 5 most common digraphs in the text. Write down the 5 most common characters in the text. Prepare a graph as follows: Take the most common character, say X. Calculate the RELATIVE frequency of X after 100, 200, 300, 400, 500 characters. Plot the 5 values into the graph and connect them by lines. Using different colors, repeat for the remaining four characters.
c) Do the same as b) but for an article in a foreign language. Tell me which language was used. Point out the main differences in your statistical analysis between English and the foreign language.
Decipher the following ciphertext, obtained with a monoalphabetic cipher. Briefly describe the your work and email me the description and the plaintext. You don't have to transcribe the plaintext into proper English with spaces and punctuation. Work alone!
rdxpdissxdvsyhkfsydhkqhfsyvbqhkjpfpvdhksbiftqcpsyrdiinyrdjbdiiuvderqshsutadrfsyedhjppcvprp hkrapmdjrvpjrsuvpdiqrfqjrapvpnyrqhmqjqnipfsykcvsndnifiqxpdkpmqepradrapicjfsyjppbyeabsvpsuq rjeqphrqjrjtsvxqhldrepvhrappyvscpdhsvldhqodrqshusvhyeipdvvpjpdveaadmpbdkpjsbpcvslvpjjqhrad rkqvperqshtqrarapdicadbdlhprqejcpervsbprpvtaqeaadjnpphvqkqhldnsdvkrapqhrpvhdrqshdijcdepjrd rqshjqheprtsrasyjdhkdhkpipmphcafjqeqjrjnpiqpmpradrbphrdipgpveqjpqhniqhkhpjjvpuiperjrapvpdi qrfsusyvyhqmpvjpshifdnsyrusyvcpvephrsutaqeabdhqupjrjdjrapxqhksubdrrpvdhkphpvlftpedhcpvepqm pbsvpradhjpmphrfcpvephreshjqjrjsujsediipkkdvxphpvlfcafjqeqjrjjdfdhkbsvpradhrtphrfcpvephrqj kdvxbdrrpvhpqrapvsutaqeaaybdhjedhkqvperifkprperjsudvnyrjeqphrqjrjuppiepvrdqhqrbyjrpgqjrcdv rifnpedyjpsuraplvdmqrfqrpgpvrjshrapmqjqnipyhqmpvjpraqjtppxepvhjeqphrqjrjcyniqjapkdhdhdifjq jsukdrduvsbrapjcpervsbprpvtaqeakprperjjyndrsbqecdvrqeipjeshjrdhrifnsbndvkqhlpdvrarapfqheiy kppgeppkqhlifvdvpdhrqbdrrpvcdvrqeipjradredhvpjyiruvsbrapnvpdxksthsukdvxbdrrpvrapfdvpediipk csjqrvshjdijsxhsthdjdhrqpipervshjrapfadmprapjdbpbdjjdjpipervshjnyrpipervshjadmpdhpldrqmpea dvlpdhkcsjqrvshjadmpdcsjqrqmpeadvlpjeqphrqjrjnpiqpmpkdvxbdrrpvesiiqkpjjciqrrqhlqhrscdqvjsu pipervshjdhkcsjqrvshjjsrapdnqiqrfrspgdbqhpcsjqrvshjqhkprdqiesyikapicqhcvsmqhlrappgqjrpheps ukdvxbdrrpv
Decipher the following ciphertext, obtained with a Vigenere cipher. Show work! Identify the author and title of the plaintext.
asbncyageanuxtmggzrbyonttgrlfthsdjzbjccedrvwqlmedqrwbtlfnseiicnkuirwigydwinguyxodrfwlfwfth zxwsueilrvcoyippyvcyiztsslndjmciyvugydnwvqaffmgjvjocydxzrwyogkllboylnftrgliycflefwbpjmxrgh xqcsjvrrzecytefkytmodqzrhwsdttehmphfthfdppntpxvqftygdjnvwjnttlrkywxiwegdnlwmhynoawuzrivvoa jahiqwimyfwiclweodthvpuryaueuxapjqchhooxmgrlnvqpmqtsadheccjipoineeilruyhuehszhnsczvlbzygyd xrgkyljbteedhnyauxulmxuowmahqscowgnxmpxytxbuyrudsmgpicymixrqntpqacjkcwyuvemhxocdtggosfjipv qdntnrdvvwmaiexxvrhhuexqzhxtuftplrpplynsjqcquzrmrgnsufxwnzceczbsgliyczprvqmeuzieswycqmghgk yquzrcjdmnizumepyocfhwjhyaqmhfelyquzsssfifletwyrqtqmiguhxtnrdvfrgpgucyghmdiytaudnthrteeeoe gagivqqzhptvjhuccqsegoyyafwavwbzvetvilhrcfhhhofxihtqrqntnggrrggjyktwhsiynttsgkycinyipwmthf wiphfwueamtknyiuhinwncuoiiqpsyifxgrdhofadovqaeifwisoizluhejvygydpprqicgajwedndndpzrumthsxx gkyjbmsmfvopxrgszwbpqqapjkcnbxpcwxmequilvqptyiiszbltatiiihhebqcaulfpcspdrgnsykrezhoaczivbr jdbggvvhxwsixxuuugyzdyfhspmmaphuyovkilrvwphfdjgkyxymijergebuhmguybougiqponbqujbunlhppxghhe cacxbvwllqilrpuhukxxzlasntpzreyphtppsdhsiggtrubljetzrquybajvsrltwajpqwuvynjxvpjplrtggqieya uxvpymyrdvrluruucgnvnxsqnifxjhudsaudntnttrfdqnizushqxpxmchnpukypbigkydqqttbinsybtrqxffgtph vqwcymhiqlhprftrgesyymgpldsllppwnqueodppprhdycjiafytnekiyrwtnklefdfdiyjgujlpuftvoxnhbmiqnl hwspxwgxlmypbijdmebqxhrdnsufweqsycwqexvefjxqhgrqxpxucsjrvdydkiqzcebiwegkiclagmglmyyqsprvme iepcgkuecfhrrwbplqmxehgtnklefiicgqsssdwcyeriawiqaxxxghlthshxrhflvajxniiznucprqaebrgszkichf dlbuhebqwseqmfjipvqdhonttyagycypvirycoyzipldmvyqcefwblnaueedtzlxxordlltageyvitnetizhxxuehc nqxsymkcgdjplucksuixnttiqjythfdefrftxmchouilxeivhfnflqpfbyytnipwnsjphpthgruhyuvlgblzxaufed mduzsxuhqsixtlvvmpxmhmgvqfhsilerorbfwinll
I have used a Playfair cipher with the default parameters. The plaintext is:
oh yo us im pl et on sa id sh et he nw em us ta ll fo ur di eo fh un ge ry ou ha db et te rp la ne th ec of fi ns fo ru sb ut sh el ef th im no pe ac et il lh ec on se nt ed sa yi ng ah bu ti sh al lr eg re tt he po or ch il dr en th et wo ch il dr en ho we ve rh ad no tg on et os le ep fo rv er yh un ge ra nd so th ey ov er he ar dw ha tt he st ep mo th er sa id to th ei rf at he rg re th el we pt bi tt er ly an ds ai dt oh an se lw ha tw il lb ec om eo fu sb eq ui et gr et he ls ai dh ed on ot cr yi wi ll so on he lp yo ua nd as so on as th ei rp ar en ts ha df al le na sl ee ph eg ot up pu to nh is co at an du nb ar ri ng th eb ac kd oo rs li pp ed ou tt he mo on sh on eb ri ll ia nt ly an dt he wh it ep eb bl es wh ic hl ay be fo re th ed oo rs ee me dl ik es il ve rp ie ce st he yg li tt er ed so br ig ht ly ha ns el st oo pe dd ow na nd pu ta sm an yi nt oh is po ck et as it wo ul dh ol da nd th en go in gb ac kh es ai dt og re th el be co mf or te dd ea rs is te ra nd sl ee pi np ea ce go dw il ln ot fo rs ak eu sa nd so sa yi ng he we nt to be da ga in
The corresponding ciphertext is:
ku ua lr ce vq bi ak je nv rv bi vo tj ae lr nb gv rm ro vn ab rp yk lb ju kr do xa bi ib fh ye ia kx mi mr sc ij rm or we gk rv is ms kx ce ka vm mn bi vs uv mi ak ei kc av je ln ty od og cn rv ey us bl so xg vo hm ko kp vs hj ai kx bi rb kp vs hj ai uk sb li ou ny ka xw ak bi er si mv rm sh os ud yk lb jo dy re kx al eh os vo oj xj do xg vo wi mv eb kx os je nv kb kx iv ws bn vo wu so kx is sb xc et xg os yu nd vj en xn ku nd ei gs do xb vs ge mi be ab rq we ml lk bi uw bi vo se en hx av ak bk kf ln st gv re ak vo qv ua yo dy ej re ak ej kx iv fh oj ai iw do pj ey si dn es bv vx bl bk qh hq kb kd ve km bn nd hy ta oj sk ty kx am mn nh bh wj sv vp av kr xg vo eb ak rv ak am sk gv ne kc yu nd xn vo rx nc mv am eg ie rx ni vu nj ma rm so kx av bh wj bv ea vy nt ie vs li fh vi im wi vo uq sv xg os av re ow tl xk yu do ij is wi bh vm hp br dn dy hq nb fe nd ln kc ku ve hm it bi ej nc rb gy hx eu yn dy kx ai ub nk wt mn hu ie en xn bu so kx is ma km cm ko ib hp ao wj ve ib jo dy es bv vc cd ao im ub xj vs yi bk rm wj on ol je dy re je ln ty vo sb kc kb ma yn yb nk
Your task is to reconstruct as much of the Playfair square as possible. Please return the square with the letter "a" in the top left position. Explain how you solved the problem. Don't forget to check that you found the correct square!
Here is the ciphertext obtained with a 2x2 Hill's System.
mkekgkvtzgmlomoebvquesfbqffhqfelkoaomwlqarwokyqfjqrybytqktamzopkaxykfzzcnmrlsqfhmwfwzoaxyk vwmlfwquiqfhktoyciaxykdofwzorlsqfhinamnmmlfwquiqfhktiegxjscaquivfhwzwrhsfqlpfwrasjqfkdgxlb wzuvhsewrazopkvswofhqfelkoaogchuacgxudsqtastwrqajrbianvymobsgxhuitobsdktampkcggcmdeasjwomd easjwozgmlmtwremomwqktkpelkyghywsectpibvcnmbcgcasugcwoddfwrefbxmkmxpfwzcxpyxquivfufdktkpye dgccwemonnksamdagxczkdaqyxindgqfmtwrmlfwankayxopmbsdxpfwaxgkvtgcnmngommoddfwzcxpyxvsrequiv fhkygharzclkkdaqoumbsqoeghsegklqfhktqecaokshznmqqmohlqjeryxpyxuyfhfhohcogcfwquivfhanikmlkt amnmnassktufivrpgcfhwrzcdavsankayxmlcygcqmkyelohsqfhkygharzclkquivjqkdaqeryxkmghtumlbiwhwz ypvsfhktyoohkdaqyxindgqfktanmdjolpqfjqtuymaqanxpcykyelcgcaiqanmkcmanxpcyctgcegmoddfwzcxpyx gxcvyxkmomajuvcykyelohzcnnuvlqjewrfhyskdaqouuvczanbskdmipertfhqfelkoaogpctrsaxykvwbmbyjrbi anhzeefhyxmdfhaifhyxmlgwcffwxmombluvaqaihdyxwqktkphuignofwzkacqffmleygyrccelveaqohfwrsmlnm iqudgcugfhkyfhcgoelkhfqgjejqnexpfwpexycawoktjqfhohsqraza
What is the matrix A used in the encryption? What is the inverse of A? What is the plaintext? Show your work!
Hint: TH and HE correspond to two of the 3 most common dighraphs in the ciphertext (not necessarily in that order).
Decipher the following message encrypted with Baby RSA, using the public key (n,e) = (4495423, 31113). Note that you are only able to do this because the primes used to obtain n are small. Describe your work!
dswebjwrbjcmswayjalc
a) Consider the binary code C={00000000,11100000,00100101,00011100}. i) What is the distance of C? ii) How many errors can C detect/correct? iii) Decode the received message 11001100, if possible.
b) Construct a binary code C of length 8, size 4 and distance 5.
c) Is there a binary code of length 8, size 7 and distance 5?